Electrode component group for a corrosion measuring system for detecting corrosion in a metal embedded in a component made of an ion-conducting material, in particular concrete

ABSTRACT

An electrode component group for a corrosion measuring system for detecting corrosion of a metal embedded in a construction component of ion-conducting material has a rod-shaped base body having a first flange member at a first end of base body and a second flange member at a second end of base body. The base body is insertable into the construction component with the first end leading. A plurality of spacer rings is positioned on the base body between the first and second flange members. The metal electrode rings and sealing rings are arranged alternatingly between the spacer rings. Each one of the metal electrode rings have an electrical line connected to a measuring circuit external to the construction component. The electrical lines are guided inside the metal electrode rings to the second end of the base body. A device for reducing a spacing between the first and second flange members is provided. The spacer rings, sealing rings, and metal electrode rings are designed such that, upon reduction of the spacing between the first and second flange members, sealing rings and electrode rings expand radially outwardly, so that the sealing rings and the metal electrode rings, after insertion of the electrode component group into a hole provided in the construction component, are brought into intimate contact at a wall of the hole upon reduction of the spacing between the first and second flange members.

BACKGROUND OF THE INVENTION

The invention relates to an electrode component group for a corrosionmeasuring system for detecting corrosion in a metal embedded in acomponent made of an ion-conducting material, especially concrete.

Such ion-conducting materials, used for making components in which theelectrode component group is used, are especially mineral constructioncomponents such as mortar, cement, concrete etc. Steel parts embedded inconcrete, such as profiled steel supports or reinforcement inserts ofconstruction steel, in general, are permanently protected againstcorrosion when the concrete construction component has been processedproperly because it is protected under a sufficiently thick concretecover. This corrosion protection is not based on the impermeability ofthe concrete to liquids, but resides in the alkalinity of the concretepore water which is, in general, of a pH value of greater than 12.5.Under these conditions, on the steel surface a thin fixedly attachedoxide layer will form which practically completely prevents corrosion.Accordingly, the steel reinforced concrete can be used for externalconstruction components exposed to the elements.

Under unfavorable conditions, especially in the case of faultyconstruction and especially in salt-containing environmental conditions,the corrosion protection relative to the reinforcements can be lost. Thereason for this may be carbonate formation of the concrete which occurswhen carbon dioxide contained in the air reacts with alkaline componentsof the cement. As a result of this, the pH value will decrease so thatno corrosion protection is present anymore. Another cause for corrosionis the penetration of chlorides into the concrete which may occur whenthe concrete component is used, for example, as a street surface or isin the vicinity of a street surface onto which de-icing salt has beendispensed. Such de-icing salt contains, in general, salt derived fromsea water or chloride-containing salts of other origins. Both processesbegin at the surface of the concrete and extend into the exterior of theconcrete to the steel parts embedded therein where their oxide layerbegins to dissolve. At the steel surface a critical state of increasingcorrosion will result without this being noticeble at the concretesurface. The corrosion damage is, in general, only then recognized whenthe corrosion of the steel has progressed and the pressure of the rustproducts causes the concrete layer to chip off.

From EP 0 364 841 B1 a corrosion measuring system for determiningcorrosion of steel embedded in concrete construction components is knownwhich comprises a multiple anode electrodes arranged spaced apart fromone another within the concrete construction component and comprised ofregular construction steel. They are arranged at different depths in theconcrete construction component and are electrically connected to atleast one cathode electrode by a measuring circuit accessible from theexterior, whereby the cathode electrode is comprised of a more noblematerial. By electrically connecting one of the anode electrodes withthe cathode electrode, the corrosion state of the respective anodeelectrode and thus the progress of corrosion in the concreteconstruction component can be determined. In the known corrosionmeasuring system, it is necessary to integrate the individual anodeelectrode and cathode electrodes during manufacture of the concreteconstruction component which does not allow for subsequent corrosiontesting of concrete construction components which have not been providedinitially with such a corrosion measuring system.

From U.S. Pat. No. 2,947,679 an arrangement for determining thecorrosion rate of different materials is known. At the outer surface ofa tubular support member electrode rings of the materials to be testedare arranged spaced to one another. At one end of the tubular supportmember, comprised of insulating material, a reference electrode isarranged. All electrodes are provided with lines which are guidedthrough the interior of the tubular support member and are connectableto a measuring circuit. The entire arrangement can be inserted into abath containing a corroding liquid, for example, an acidic aqueoussolution. By electrically connecting the different measuring electrodesto the reference electrode, the different corrosion of the measuringelectrodes can be determined. An introduction of this system directlyinto a concrete construction component is not envisioned.

It is an object of the invention to provide an electrode component groupfor a corrosion measuring system for determining corrosion of a metalembedded in a concrete construction component which electrode componentgroup can be retrofitted in a simple manner into a concrete constructioncomponent whose corrosion is to be measured.

SUMMARY OF THE INVENTION

With the inventive electrode component group that can be retrofittedinto a hole or a bore of the component a safe, large surface area, andpermanent contact between the electrode rings and the concrete isachieved. By means of the sealing rings positioned between the electroderings and resting sealingly at the construction component, geometricmeasuring areas are provided which are separated from one another andare correlated with a respective electrode ring so that a precisecorrosion analysis is possible.

Advantageous further embodiments of the inventive electrode componentgroup are provided in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in the following with the aid ofschematic drawings in an exemplary manner and with further details.

It is shown in:

FIG. 1 a longitudinal section of a first embodiment of an electrodecomponent group;

FIG. 2 a cross-section of the electrode component group according toFIG. 1, according to section plane II—II;

FIG. 3 a longitudinal section of a second embodiment of the electrodecomponent group.

DESCRIPTION OF PREFERRED EMBODIMENTS

According to FIG. 1, the electrode component group identified by 2comprises a rod-shaped base body 4 which is a support member for theentire arrangement and ends to the left of the figure in a flange member6 with widened diameter. The base body 4 has a recessed, respectively, alongitudinal slot 8 from where a through channel 10 extends to theflange member 6.

At a spacing from the flange member 6 the base body 4 has a threadedarea 12 onto which a nut 14 is threaded. From the interior of the basebody a channel 16 extends through the base body to the right end shownin FIG. 1. The nut 14 rests, optionally with intermediate arrangement ofa washer, at a clamping flange 18 which is longitudinally slidablyarranged on the support member 4 and has an outer diameter that isgreater than that of the flange member 6.

The base body 4 supports between the flange members 6 and 18 a pluralityof spacer rings 20 having lateral surfaces ending, in a direction towardan outer circumference, in slanted surfaces 22. Between two spacer rings20 electrode rings 24 and sealing rings 26 are arranged alternatinglywhereby preferably between the respective outermost spacer rings 20 andthe flange member 6 or 18 a sealing ring is arranged.

The sealing rings, comprised of elastic and electrically insulatedmaterial, have preferably a round cross-section. The electrode rings 24,comprised preferably of construction steel, have a trapezoidcross-section whereby the slant of its lateral surfaces matches theslant of the slanted surfaces 22.

The size of the spacer rings 20, electrode rings 24, and sealing rings26 is such that the outer circumference in the loose state of thearrangement does not project past the outer circumference of the flangemember 6.

Opposite the nut 14, the base body 4 ends in a bushing 30 in which oneelectrical line 32 for each one of the electrode rings 24 is connectedto a contact (not shown). The lines 32 are guided through thelongitudinal slot 8 into the interior of the support member 4.

External to the nut 14 the base body has flattened portions 33 forattachment of a tool, for example, a wrench. Furthermore, a radialopening 34 is provided through which the channel 16 is accessible. Theentire arrangement is inserted into a bore 35 which is provided in aconcrete construction component 36 and has an inner diameter whichcorresponds substantially to the outer diameter of the flange member 6.

The assembly of the afore disclosed arrangement is as follows.

The sealing rings 26, spacer rings 20, and electrode rings 24 are firstslipped onto the base body 4 in the aforementioned sequence. The lines32 connected to the electrode rings 24, for example, by soldering, areintroduced into the longitudinal slot 8 and pushed through the channel16 so that they project from the right side. The clamping flange 18 ispushed onto the base body 4, and the nut 14 is then screwed on so thatthe rings are secured between the flange members 6 and 18 on the basebody 4. The lines 32 are connected to the connector bushing 30 which isfastened to the base body 4. The arrangement is now complete formounting in a bore 35 of the concrete construction component 36. Forthis purpose, the arrangement, with the flange member 6 leading, isinserted into the bore 35 until the clamping flange 18 abuts theexternal side of the concrete construction component 36. Advantageously,between the clamping flange 18 and the concrete construction component36 a seal (not represented in FIG. 1) is positioned. The nut 14 is nowrotated whereby the base body 4 is secured at the flattened portion 33by a wrench. The flange member 6 is moved to the right of FIG. 1together with the base body 4 so that the spacing between the flangemember 6 and the clamping flange 18 is reduced. The spacing between thespacer rings 20 is also reduced so that the sealing rings 26 and theelectrode rings 24 are moved outwardly, respectively, are spreaded. Thesize of the slanted surfaces 22 of the spacer rings 20 relative to thesealing rings 26 is such that the spacer rings 20 will come into directcontact with one another before the sealing rings 26 are outwardlyspread to unacceptable limits that could cause damage. The sealing rings26 are thus brought into perfect abutment at the inner wall of the bore35 and seal individual bore segments relative to one another. Uponfurther tightening of the nut 14, the electrode rings 24 which willspread only with application of greater forces in comparison to thesealing rings 26, are spread, respectively, enlarged with regard to theouter diameter so that they are also in a fixed contact at the innerwall of the bore 35. The electrode rings 24 can be slotted forfacilitating the spreading action (FIG. 2). For intensifying the contactbetween the outer circumference of the electrode rings 24 and the innerwall of the bore 35, the outer circumference of the electrode rings 24are provided with fluting or knurling. The entire arrangement, forsufficient tightening of the nut 14, is secure and safely held withinner contact in the bore 35. Subsequently, a specialty grease ispressed through the opening 34 into the interior of the base body 4which fills the space between the rings and can enter the bore 35through the channel 10. The transition area from the connecting bushing30 to the support member 4 and the opening 34 is then closed by castresin so that the entire arrangement is hermetically sealed to theexterior.

The electrode component group 2 inserted into the bore 35 and fastenedtherein thus provides a sensor divided into separate measuring chamberswhereby each measuring chamber contains an electrode ring 24 by whichthe introduction of pollutants into the concrete can be followed in astepwise manner since the individual electrode rings are connected in amanner known to a person skilled in the art to a measuring circuit. Acathode of stainless steel or titanium coated with platinum oxide can beused as a counter electrode inserted into the concrete construction part36. The individual electrode rings 24 can also electrically connected toone another so that for different corrosion states measurable currentswill flow. Alternatively, one of the electrode rings 24 can be comprisedof noble metal and can serve as a cathode. It is understood that theelectrode rings 24 are preferably comprised of the same material as thereinforcement of the concrete construction component 36 whose corrosionstate is to be detected. The coupling of electrode rings 24 to theconcrete can be realized by direct AC current resistance measurementbetween the electrode rings 24. As mentioned above, with the disclosedspreading of the rings closed measuring zones are provided inpredetermined positions so that, for example, chloride can reach theelectrode rings only laterally from the exterior and no chloridetransport along the walls of the bore 35 is possible.

The inner sealing action of the entire arrangement ensures a corrosionprotection its metal parts. In the area of the connecting bushing 30 aresin fill is provided which is electrically insulated and rigid. In thearea of the rings pressure application with grease is provided so thatthe grease extends into the bore hole.

It is understood that the electrode rings 24 must not be in electricalcontact with one another via the spacer rings 20 and the base body 4.This can be realized by an expedient selection of materials, forexample, by embodying the base body 4 or the spacer rings 20 of plasticor by providing a respective coating thereon. It is understood that foravoiding overload of the sealing rings 26 the spacer rings 20 must beprovided with respective lateral projections which ensure the requiredspacing.

FIG. 2 shows a cross-sectional view of the arrangement of FIG. 1. A slot38 of the electrode ring 24 is shown which facilitates spreading butmust not be present for an electrode ring which is sufficientlyyielding. Also shown is a soldering connection 40 of the line 32 to theelectrode ring 24. The base body 4 is provided with a longitudinalgroove 40 which receives a rod 42 comprised, for example, of PVC whichengages corresponding recesses of the spacer rings to secure themagainst rotation (not shown in FIG. 1). The rotational securing actioncan also be realized by a projection extending along the base body 4which engages a corresponding recesses of the spacer rings 20 and alsooptionally of the clamping flange 18.

FIG. 3 shows a different embodiment of the electrode component group ofFIG. 1.

The clamping flange 18 is hat-shaped and comprises an inner bottom 44and an outer edge flange 46 having a transition into one another by acylindrical area 48. The rings 20, 24, and 26 are embodied such thatthey are supported partially by the base body 4 and partially by thecylindrical area 48. The connecting bushing 30 provided at one end ofthe base body 4 is received in the interior of the hat-shaped clampingflange 48 so that this interior can be covered by a cap 50. The edgeflange 46 is inserted into the recess of the concrete constructioncomponent 36 provided at the edge of the bore 35 with interposition ofsealing ring 52 so that the entire arrangement is flush to the exterior.Upon use, the cap 50 is removed and a known measuring circuit isconnected to the connecting bushing 30 which optionally comprises acathode electrode separate from the electrode component group 2 andinserted into the concrete construction component 36.

The present invention is, of course, in no way restricted to thespecific disclosure of the specification and drawings, but alsoencompasses any modifications within the scope of the appended claims.

What is claimed is:
 1. An electrode component group for a corrosionmeasuring system for detecting corrosion of a metal embedded in aconstruction component of ion-conducting material, said electrodecomponent group comprising: a rod-shaped base body (4) having a firstflange member (6) at a first end of said base body (4) and a secondflange member (18) at a second end of said base body (4), wherein saidbase body (4) is insertable into the construction component with. saidfirst end leading; a plurality of spacer rings (20) positioned on saidbase body (4) between said first and second flange members (6, 18);metal electrode rings (24) and sealing rings (26) arranged alternatinglybetween said spacer rings (20); each one of said metal electrode rings(24) having an electrical line (32) connectable to a measuring circuitexternal to the construction component; said electrical lines (32)guided inside said metal electrode rings (24) through an interior ofsaid base body to said second end of said base body (4); a device (12,14) for reducing a spacing between said first and second flange members(6, 18); said spacer rings (22), said sealing rings (26), and said metalelectrode rings (24) designed such that, upon reduction of said spacingbetween said first and second flange members (6, 18), said sealing rings(26) and said electrode rings (24) expand radially outwardly, so thatsaid sealing rings (26) and said metal electrode rings (24), afterinsertion of said electrode component group into a hole (34) provided inthe construction component, are brought into intimate contact at a wallof the hole upon reduction of said spacing between said first and secondflange members (6, 18).
 2. An electrode component group according toclaim 1, wherein said metal electrode rings (24) and the metal embeddedin the construction component are comprised of identical metal material.3. An electrode component group according to claim 1, wherein saidsealing rings (26) and said spacer rings (20) are matched to one anothersuch that a radial expansion of said sealing rings (26) is limited bysaid spacer rings (20) abutting one another upon reduction of saidspacing between said flange members (6, 18).
 4. An electrode componentgroup according to claim 1, wherein said sealing rings (26) have acircular cross-section.
 5. An electrode component group according toclaim 1, wherein said electrode rings (24) have a trapezoidalcross-section having lateral surfaces, wherein said lateral surfaces ofsaid electrode rings (24) have a slant matching a slant of radiallyouter lateral surfaces (22) of said spacer rings (20).
 6. An electrodecomponent group according to claim 1, wherein said electrode rings (24)have a knurled outer circumference.
 7. An electrode component groupaccording to claim 1, wherein said device for reducing said spacingbetween said first and second flange members (6, 18) comprises a nut(14) and wherein said base body (4) has a threaded area (12) projectingfrom said second flange member (18), wherein said nut (14) is threadedonto said threaded area (12) and wherein said second flange member (18)is movable along said base body (4) by said nut (14).
 8. An electrodecomponent group according to claim 7, wherein said second flange member(18) is hat-shaped.
 9. An electrode component group according to claim7, wherein said second flange member (18) has an end face facing awayfrom said nut (14) and wherein said end face has a seal (48).
 10. Anelectrode component group according to claim 9, wherein one of saidfirst and second flange members (18) is hat-shaped and has an interiorcovered by a cap (50), wherein said connecting bushing (30) is arrangedin said interior of said flange member (18) and is covered by said cap(50).
 11. An electrode component group according to claim 1, furthercomprising a connecting bushing (30) connected to said second end ofsaid base body (4) that is positioned external to the constructioncomponent.
 12. An electrode component group according to claim 1,wherein said base body (4) has a hollow interior and has a longitudinalslot (8), wherein said electrical lines (32) are guided through saidlongitudinal slot (8) into said hollow interior.
 13. An electrodecomponent group according to claim 12, wherein said base body (4) has athrough channel (10) at said first end and wherein said hollow interiorof said base body (4) is filled with grease introduced via said throughchannel (10).
 14. An electrode component group according to claim 13,further comprising a means (40, 42) for securing said base body (4) andsaid spacer rings (20) against rotation.
 15. An electrode componentgroup according to claim 1, wherein said means (40, 42) secures saidsecond flange member (18) relative to said base body (4) so that norelative rotation between said second flange member (18) and said basebody (4) is possible.